I hear you. I also use those same techniques and I block more than I repeat. Sometimes doing voice impressions can help. I'm not sure but I think there's a psychological aspect to it. When you do a voice impression and pretend to be someone else, you temporarily disconnect from own ego. When you do that, your self esteem no longer has any effect on your speech because you are pretending to be someone else. I guess that's why a lot of stutterers can act on stage without stuttering.